This invention relates generally to single or multi-pole circuit breakers, and more particularly to circuit breakers having improved movable contact holding structures.
The basic functions of circuit breakers are to provide electrical system protection and coordination whenever abnormalities occur on any part of the system. The operating voltage, continuous current, frequency, short circuit interrupting capability, and time-current coordination needed are some of the factors which must be considered when designing a breaker. Government and industry are placing increasing demands upon the electrical industry for interrupters with improved performance in a smaller package and with numerous new and novel features.
Stored energy mechanisms for use in circuit breakers of the single pole or multi-pole type have been known in the art. A particular construction of such mechanisms is primarily dependent upon the parameters such as rating of the breaker. Needless to say, many stored energy circuit breakers having closing springs cannot be charged while the circuit breaker is in operation. For that reason, some circuit breakers have the disadvantage of not always being ready to close in a moment's notice. These circuit breakers do not have, for example, an open-close-open feature which users of the equipment find desirable.
Another problem present in some prior art circuit breakers is that associated with matching the spring torque curve to the breaker loading. These prior art breakers utilize charging and discharging strokes which are each 180.degree.. The resulting spring torque curve is predetermined, and usually cannot be matched with the breaker loading. Such a predetermined curve mandates that the elements associated with the breaker be matched for this peak torque rather than be matched with the breaker load curve.
An additional problem present in the prior art circuit breakers is associated with the means for connecting the movable contact to one of the stationary contacts. These prior art connections generally included the use of braids or laminations which were secured to both the movable contact and one of the stationary contacts, and more particularly, the load side stationary contact. These braids are not always desirable, in that they may include some slack which could interfere with normal breaker operations.
Still another shortcoming present in the prior art breakers concerns the economics of utilizing many different parts for differing sizes of breakers, and the necessity of stockpiling or inventoring the numerous sizes. Economies can be made if the same member can be utilized to function in more than one size circuit breaker. In addition to minimizing the inventories required for each size, it is also desirable if the parts which are required can be unitized; that is, if some of the parts can be made so as to perform more than one function, the total number of parts involved in the breaker may be minimized.